java - 从Java中的另一个线程访问变量

Question

我正在编写一个在 Java 上使用套接字通信的小代码，并且我正在尝试执行以下操作:

1. 接收 JSON 对象并解析它[完成]
2. 如果收到的命令是登录，则开始登录[完成]

3. 将登录过程的结果打印到套接字这是我遇到问题的最后一部分，我的代码如下:

   public class LoginActivity extends Activity {
   
   private Button btnLogin;
   private Button btnDemo;
   private EditText edtLogin;
   private EditText edtSenha;
   
   private ProgressDialog pd;
   
   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_login);
   
       btnLogin = (Button)findViewById(R.id.btnLogin);
       btnDemo = (Button)findViewById(R.id.btnDemo);
       edtLogin = (EditText)findViewById(R.id.edtLogin);
       edtSenha = (EditText)findViewById(R.id.edtSenha);
       pd = new ProgressDialog(this);
   
       new Thread(new Runnable(){
           public void run(){
               try {
                   String inMsg;
                   JSONObject fromClient;
                   String cmd;
                   JSONArray args;
                   ServerSocket server;
                   Socket client;
                   BufferedReader in;
                   PrintWriter out;
                   //TODO: Getting reconnects on a proper method
                   System.out.println("Waiting for client on port 8888");
                   server = new ServerSocket(8888);
                   client = server.accept();
                   System.out.println("Just connected to " + client.getRemoteSocketAddress());
                   in = new BufferedReader(new InputStreamReader(client.getInputStream()));
                   out = new PrintWriter(client.getOutputStream(), true);
                   while(true)
                   {
                       inMsg = in.readLine();       
                       if (inMsg == null)
                       {
                           System.out.println("Waiting for client on port 8888");
                           client = server.accept();
                           System.out.println("Just connected to " + client.getRemoteSocketAddress());
                           in = new BufferedReader(new InputStreamReader(client.getInputStream()));
                           out = new PrintWriter(client.getOutputStream(), true);
                           continue;
                       }
                       fromClient = new JSONObject(inMsg);
                       System.out.println("In: " + fromClient);
                       cmd = fromClient.getString("command");
                       args = new JSONArray(fromClient.getString("args"));
                       if(cmd.equals("login")){
                           final String login = args.getString(0);
                           final String pwd = args.getString(1);
                           AndroidUtil.mostrarProgressoAguarde(LoginActivity.this, pd);
   
                           new Thread(new Runnable() {
                               public void run() {
                                   PagPop.getInstance().logar(LoginActivity.this, login, pwd, new ServidorListener<Cliente>() {
                                       @Override
                                       public void recebeuResposta(String mensagem, RespostaServidor<Cliente> resposta) {
                                           handleResposta(mensagem, resposta);
                                       }
                                   });
                               }
                           }).start();
                           //out.println(mensagem);
                       }
   
                       else 
                       {
                           out.println("Received");
                       }
                   }
               } catch (Exception e) {
                   e.printStackTrace();
               }
           }
       }).start();
       btnLogin.setOnClickListener(new OnClickListener() {
           @Override
           public void onClick(View v) {
               final String login = edtLogin.getText().toString();
               final String senha = edtSenha.getText().toString();
               System.out.print("Tentando Logar");
   
               AndroidUtil.mostrarProgressoAguarde(LoginActivity.this, pd);
   
               new Thread(new Runnable() {
                   public void run() {
                       PagPop.getInstance().logar(LoginActivity.this, login, senha, new ServidorListener<Cliente>() {
                           @Override
                           public void recebeuResposta(String mensagem, RespostaServidor<Cliente> resposta) {
                               handleResposta(mensagem, resposta);
                           }
                       });
                   }
               }).start();
           }
       });
   

在代码中间附近，我尝试在 //out.println(mensagem); 打印出所需的变量失败； 如果我尝试编译我的代码，则会发生以下情况:

[javac] /android/demo/LoginActivity.java:107: error: local variable out is accessed from within inner class; needs to be declared final

[javac] out.println(mensagem);

我怎样才能将变量mensagem从那里传输出来，以便我可以从if级别out.println它或访问out 从该方法而不使 out 最终？

Answer 1

将 PrintWriter out 声明为 Activity/fragment 中的全局变量